1. Field of the Invention
The present invention relates generally to a material flow monitoring and equalization system, and more particularly to a system for measuring and balancing the flow of seeds in an air seeder for crop planting.
2. Description of the Related Art
The general principle of an air seeding system is to dispense seeds and/or other particulate matter (fertilizers, herbicides, etc.) from a hopper or other container into a moving flow of air, where the moving air will carry it through a series of branching tubes and manifolds to a point where it will ultimately be deposited into the soil. The particulate matter is typically metered in a controlled fashion as it is dispensed from the hopper, allowing the total rate of material distributed to be controlled. However, once the material leaves the hopper, it is difficult to determine precisely which portion takes which specific path through the branching network of tubes to eventually make its way to the end of the seed tubes and be placed into the soil.
An air seeding system represents a complex fluid dynamics problem, in which a single initial flow of air and suspended seeds may be continuously divided and redirected through multiple tubes to manifolds where it is then split off into branching seed tubes of varying lengths to a point of eventual discharge into the soil. Sharp turns, bends, and forks in the distribution tubes cause restrictions on the material flow, and make balancing the system for seed and other particulate dispersal problematic. A modern air seeder may plant well over 100 rows of seeds simultaneously. If a partial or full blockage develops in one or more of the particulate flow tubes, air flow (and, therefore, particulate flow) increases proportionately in the remaining tubes, further complicating the balancing problem. To optimize the distribution of material and maintain an even balance of distribution, an air seeding system must employ some type of particulate flow balancing system which balances the amount of particulate material flowing in the distribution tubes (the particulate flow path), a subsystem by which the flow can be adjusted so that an operator can balance the system, and another subsystem to detect particulate flow disruption or blockage during use should field conditions cause the system to become unbalanced.
It should be noted that the term “blockage” will be used generally throughout the specification to refer to either a full and a partial blockage in some part of the air seeding system. A partial blockage will still allow some amount of air and material to flow past it, but will reduce the flow noticeably. A full blockage will not allow any material to flow past it (although it may be possible for a small amount of air to leak past a full blockage).
An important metric for measuring the balance of an air seeder system is the “Coefficient of Variation” (CV), which is defined as a percentage difference between sets of final seed runs. The sets could range from a few final runs, to an entire manifold, to the entire width of the seeder. The Prairie Agricultural Machinery Institute has published guidelines for CV values as its basis for rating the uniformity of distribution for seeding implements. These guidelines describe a rating scale wherein: a CV greater than 15% is unacceptable, a CV between 10% and 15% is acceptable, and a CV less than 10% is good.
Heretofore there has not been available an air seeder manifold system with the advantages and features of the present invention.